This invention relates generally to electrical connectors and relates more particularly to modular electrical connectors for electrically interconnecting printed circuit boards and the like via a flexible circuit.
Electrical connections are frequently made between flexible circuits and printed circuit boards. In many cases, flexible circuits are used to connect multiple printed circuit boards to one another.
A flexible circuit generally includes a flat, flexible substrate upon which electrical conductors or traces are formed. The electrical conductors typically terminate at end portions of the flexible circuit. Terminations formed at these end portions may comprise raised features such as conductive protuberances or bumps, which are used to effect electrical connection to corresponding contact pads formed upon a mating surface of a printed circuit board or the like. Such bumps typically comprise a malleable metal such as gold, which readily bonds with the corresponding aluminum contact pads. Thus, such bumps may be utilized to effect electrical interconnection of flexible circuits and rigid circuits, such as printed circuit boards and the like.
When electrically connecting a flexible circuit with a printed circuit board, the bumps of the flexible circuit are pressed firmly against corresponding conductive contact pads of the printed circuit board in order to provide a reliable electrical connection. A clamping system is typically defined by a connector which provides the compression force necessary to maintain the desired mechanical and electrical contact between the bumps and the contact pads. The connector thus facilitates reliable electrical connection of the flexible circuit and the printed circuit board.
It is known to use flexible circuitry to connect printed circuit boards to one another according to various different configurations or relative orientations of the printed circuit boards. According to a first exemplary contemporary configuration, spaced apart, generally coplanar printed circuit boards are bridged or attached to one another via flexible circuitry which extends therebetween, so as to define a jumper. According to a second exemplary contemporary configuration, stacked, generally parallel printed circuit boards are interconnected via flexible circuitry, so as to define a mezzanine. According to a third exemplary configuration, generally orthogonal printed circuit boards are attached to one another via flexible circuitry, so as to define a backplane.
More particularly, according to the contemporary coplanar configuration, two generally coplanar printed circuit boards are electrically interconnected with one another via a flexible circuit which extends in a bridge-like fashion therebetween. Clamping connectors are utilized to attach each end of the flexible circuit to one of the printed circuit boards by urging contact bumps of the flexible circuit toward corresponding contact pads formed upon each printed circuit board.
Such contemporary clamping connectors each generally comprise two elongated clamp members between which one end of the flexible circuit and a portion of the printed circuit board are sandwiched, such that when fasteners are used to draw the two elongated clamp members toward one another, the flexible circuit and the printed circuit board are compressed between the two elongated clamp members. In this manner, the conductive bumps of the flexible circuit are brought into intimate mechanical contact with the complimentary pads of the printed circuit board.
According to the contemporary parallel configuration, the two printed circuit boards are positioned in a stacked configuration, e.g., one above the other, and a spacer (along with the flexible circuit and two printed circuit boards) is disposed between two elongated clamp members of a single clamp. The spacer maintains the two printed circuit boards a desired distance from one another. Thus, in the parallel configuration, a single clamp effects desired electrical contact between the first printed circuit board and a first end of the flexible circuit, as well as between the second printed circuit board and a second end of the flexible circuit.
According to the contemporary orthogonal configuration, the spacer is configured so as to position the two printed circuit boards generally at right angles with respect to one another. Each of two separate clamp members independently clamps one of the two printed circuit boards and one end of the flexible circuit to a common spacer. That is, one of the two clamp members clamps one printed circuit board and one end of the flexible circuit to the spacer and the other of the two clamp members clamps another printed circuit board and the other end of the flexible circuit to the same spacer. The spacer is configured so at to orient the two printed circuit boards generally orthogonal to one another when the two printed circuit boards are clamped to the spacer.
Thus, according to contemporary practice, a variety of different configurations of connectors or clamp members are required in order to facilitate the interconnection of printed circuit boards at various different desired orientations with respect to one another.
One disadvantage commonly associated with such contemporary connectors is the need to manufacture a separate, custom spacer for each unique application which requires a spacer. For example, when it is desired to electrically connect two parallel printed circuit boards to one another in a mezzanine fashion, a particular, unique spacer must be fabricated which provides the desired orientation and spacing of the two printed circuit boards relative to one another. Similarly, when it is desired to position two printed circuit boards orthogonal to one another in a backplane fashion, it is necessary to fabricate a spacer which facilitates the desired orthogonal positioning of the printed circuit boards.
Moreover, it is expensive to fabricate such custom spacers and it is expensive and inconvenient to maintain an inventory of such unique spacers in an attempt to anticipate common printed circuit board mounting configurations.
Another disadvantage associated with such contemporary connectors is the relatively high material cost of the spacer. The spacer in such contemporary clamping systems is fabricated from metal. As those skilled in the art will appreciate, the fabrication of spacers from metal is undesirably time consuming and expensive. Frequently, such metal spacers are individually machined.
In view of the foregoing, it is desirable to provide a connecting system which facilitates the electrical interconnection of printed circuit boards and the like utilizing a flexible circuit, wherein at least some portion of each connector is standardized such that the standardized portions may be utilized in a variety of different connector configurations so as to reduce inventory requirements. It is also desirable to provide a connecting system wherein the use of lower cost materials is facilitated.
In accordance with the principles of the present invention, an electrical connector for interconnecting printed circuit boards and the like with flexible circuitry and for mounting printed circuit boards and the like at desired positions relative to one another is provided.
Although the present invention is described and illustrated herein as effecting the interconnection of two printed circuit boards, such is by way of example only and not by way of limitation. Those skilled in the art will appreciate that various different, generally rigid, electronic devices may be interconnected using the connecting system of the present invention.
The clamping system of the present invention comprises an inboard clamp member which has a body configured to cooperate with a generally complimentary outboard clamp member, so as to capture a portion of at least one printed circuit board and a portion of a flexible circuit between the inboard clamp member and the outboard clamp member in a manner which facilitates electrical connection of the printed circuit board and the flexible circuit. The body of the inboard clamp member is also advantageously configured to facilitate attachment of a spacer thereto. The spacer also has a body and is configured to facilitate desired positioning of the two printed circuit boards with respect to one another. Preferably, attachment of the body of the inboard clamp member and the spacer to one another is accomplished via a latch, such that the body and the spacer can be conveniently snapped together during a simple assembly process. The latch is preferably formed such that the inboard clamp member and the spacer can be simply snapped together.
According to the present invention, the spacer of the clamping system is an interchangeable element (with respect to the inboard and orthogonal clamp members) which is used to facilitate desired positioning of two printed circuit boards or the like with respect to one another. The spacer is attached to two inboard clamp members, so as to facilitate mechanical attachment of two printed circuit boards to one another, as well as to facilitate electrical communication between the two printed circuit boards via a flexible circuit. The configuration of the spacer determines the relative position of the two printed circuit boards which are mechanically attached to one another therewith. Thus, by selecting a spacer having a desired configuration, the spacing, angle and/or orientation of the two printed circuit boards relative to one another is defined.
It is important to note that spacers can be configured so as to have various thicknesses, which provide various relative spacings of the two printed circuit boards in the parallel configuration, for example. The spacer can also be formed so as to have various different angles between the first and second inboard clamp members attached thereto, so as to similarly provide various different angles between two printed circuit boards mechanically attached to one another therewith, such as in the orthogonal configuration, for example.
As those skilled in the art will appreciate, the clamping system of the present invention advantageously provides an improved method and device for electrically connecting two printed circuit boards with a flexible circuit (and consequently for connecting the printed circuit boards with one another). The maintenance of a comparatively standard inventory improved, so as to desirably reduce manufacturing and inventory costs. The inboard and outboard clamp members are standardized and are therefore usable in all these basic configurations, e.g., coplanar, parallel and orthogonal. Different spacers are required for the parallel and orthogonal configurations and no spacer is required for the coplanar configuration. Assembly costs are reduced by facilitating simple snap-together construction of the inboard clamp members and the spacer.
Thus, according to the present invention, a spacer may be specifically configured to facilitate the electrical interconnection of two printed circuit boards which are oriented generally parallel to one another, which are oriented generally orthogonal to one another, as well as which are disposed at various other angles and/or orientations with respect to one another. Indeed, the inboard and outboard clamp members may be used without a spacer, so as to facilitate the interconnection of two printed circuit boards which are at various angles and/or orientations with respect to one another. Of course, when omitting the spacer some other means for maintaining the desired mechanical mounting of the printed circuit boards must be provided.
Since the use of an interchangeable spacer facilitates the mounting of printed circuit boards at various different orientations with respect to one another, the need for custom mounting and/or clamping hardware is mitigated. Thus, rather than having a comparatively larger inventory containing a dedicated or custom clamp assembly for each desired orientation of printed circuit boards, an inventory containing only standard inboard and outboard clamp members and the desired variety of spacers may be provided instead.
Further, the use of such interchangeable spacers generally facilitates fabrication of the spacers utilizing less expensive materials, thereby desirably lowering the overall cost of the connector. Typically, such connectors, including any spacing component thereof, have been fabricated from metal, so as to provide the desired structural strength and durability. However, according to the present invention, the inboard and outboard clamping members may be fabricated from metal and the spacer can be fabricated from a less expensive material, such as plastic.
As those skilled in the art will appreciate, the inboard and outboard clamping members are portions of the connector assembly which are generally subject to higher stress than the spacer. Indeed, in those applications wherein the printed circuit boards are generally parallel with respect to one another, the spacer is subjected mostly to a compressive force, which does not require substantial structural strength. The inboard and outboard clamp members mitigate, spread or relieve a substantial portion of the stress applied to the spacer. Therefore, while it is generally necessary that the inboard and outboard spacers be fabricated of a durable material such as metal, according to the present invention the spacer may generally be formed of a less durable material such as plastic.